1. Field of the Invention
The present invention relates to a system and method for oil gasification. In particular, the present invention relates to a system and method for oil gasification while reducing wastewater and purification systems.
2. Related Art
Gasification is among the cleanest and most efficient technologies for the production of power, chemicals and industrial gases from hydrocarbon feedstocks, such as coal, heavy oil, and petroleum coke. Gasification converts hydrocarbon feedstocks into clean synthesis gas, or syngas, composed primarily of hydrogen (H2) and carbon monoxide (CO). In a gasification plant, the feedstock is mixed with oxygen (O2) and they are injected into a gasifier. Inside the gasifier, the feedstock and the O2 are subjected to a high-temperature and a high-pressure. As a result, the feedstock and the O2 break down into syngas.
In addition to H2 and CO, the syngas contains other gases in small quantities, such as ammonia, methane and hydrogen sulfide (H2S). As much as 99% or more of the H2S present in the syngas can be recovered and converted to elemental sulfur form and used in the fertilizer or chemical industry. Ash and any metals are removed in a slag-like state, and the syngas is cleansed of particulates. The clean syngas is then used for generating electricity and producing industrial chemicals and gases.
Gasification allows refineries to self-generate power and produce additional products. Thus, gasification offers greater efficiencies, energy savings, and a cleaner environment. For example, a gasification plant at a refinery in El Dorado, Kansas converts petroleum coke and refinery wastes into electricity and steam, making the refinery entirely self-sufficient for its energy needs and significantly reducing waste and coke handling costs. For these reasons, gasification has increasingly become popular among refiners worldwide. Currently, there are several hundred gasification plants in operation worldwide.
As part of the gasification process, some water must be purged due to the high levels of contaminants and inert corrosive salts that could damage the system. The wastewater must be treated to enable it to meet environmental quality standards. The removal of large amounts of wastewater necessitates the addition of a substantial amount of high quality intake water to maintain the system""s equilibrium. The process of treating wastewater and adding xe2x80x9cnewxe2x80x9d intake water is extremely costly. Additionally, to remove ammonia from the water within the system, an expensive reflux stripper is typically required. In some systems, even after the removal of the ammonia and a large percentage of contaminants, the purged water still does not meet strict environmental regulations.
For these reasons, a need has been recognized by the inventors for an oil gasification system that does not require expensive water treatment devices and does not require an input of additional water to the system while still meeting strict environmental standards.
The present invention solves the problems with, and overcomes the disadvantages of, conventional oil gasification systems.
The present invention relates to a system and method for oil gasification. In particular, the present invention relates to an apparatus and method for oil gasification while reducing wastewater. In one aspect of the present invention, a process configuration for use with an oil gasification system is provided. The processing apparatus comprises a flash gas condensing section, a syngas washing section, and a syngas cooling section. The flash gas condensing section is configured to receive flash gas from the oil gasification system. There is a vacuum pump coupled to the flash gas condensing section which is configured to extract vapor from the flash gas condensing section. The vacuum pump has a water outlet coupled to the flash gas condensing section, and a dry flash gas outlet. The syngas washing section has a wash water inlet, a spent wash water outlet, a cold syngas inlet and a syngas outlet. The syngas cooling section is configured to receive spent wash water from the syngas washing section and to receive seal and flush water from the flash gas condensing section.
In another aspect of the invention, an oil gasification system is provided. The oil gasification system comprises a partial oxidation gasifier configured to receive feedstock and water and to emit hot syngas. There is a syngas quenching and soot scrubbing section coupled to the partial oxidation gasifier and a soot water vacuum flashing section coupled to the syngas quenching and soot scrubbing section. A flash gas condensing section is coupled to the soot water vacuum flashing section. There is a soot filter configured to receive cool soot water from the soot water vacuum flashing section and to output filtrate and a soot filter cake. A syngas washing section is provided which has a wash water inlet, a spent wash water outlet, a cold syngas inlet and a syngas outlet. A syngas cooling section is provided.
In a further aspect of the present invention, a method for performing oil gasification is provided. The method comprises: providing feedstock and water to an oil gasification system; receiving flash gas from the oil gasification system at a flash gas condensing section; extracting vapor generated by the flash gas condensing section; returning water produced by the extracting step to the flash gas condensing section; outputting dry flash gas produced by the extracting step; receiving spent wash water at a syngas cooling section from a syngas washing section; and outputting washed syngas from the syngas washing section.
Accordingly, the present invention provides a system and method for oil gasification that eliminates costly water treatment devices and does not require an input of additional fresh, clean water to the system. The system of the present invention is a substantially closed loop system.
The system of the present invention eliminates the need for expensive water treatment devices and processes. For example, the present invention eliminates the need for a high-ammonia purge cold condensate stream, and a large, expensive ammonia stripper, and associated requirements to handle its offgas and provide it with stripping steam, as in conventional systems.
The system of the present invention eliminates the need for a contaminated process water purge stream, and thus eliminates the need for expensive wastewater treatment and any adverse environmental effects of the discharged water.
The system of the present invention does not require a steady input of fresh, clean feed water to operate and thereby reduces intake water consumption.
The system of the present invention eliminates the need for a filter-feed heat exchanger cooler by adding low-cost equipment.
The system of the present invention recycles cold syngas condensate water to the gasifier as moderator water, thereby eliminating the need to add additional water to the system.
The system of the present invention recycles most of the cold syngas condensate back to the upstream stages of syngas cooling.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned in practice of the invention.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the features, advantages, and principles of the invention.
FIG. 1 is a schematic of one embodiment of a processing apparatus of the present invention for use with an oil gasification system.
FIG. 2 is a schematic of one embodiment of an oil gasification system of the present invention.
FIG. 3 is a schematic of a component of the systems shown in FIGS. 1 and 2.
FIG. 4 is a schematic of the syngas cooling section of the systems shown in FIGS. 1 and 2.
FIG. 5 is a schematic of the flash gas condensing section of the systems shown in FIGS. 1 and 2.
FIG. 6 is a schematic of one embodiment of a method of the present invention.
FIG. 7 is a schematic of an alternative method of the present invention.
FIG. 8 is a flow schematic of results obtained using the system of the present invention.